Vitamin D 'triggers and arms' the immune system

Vitamin D is crucial to the fending off of infections, claims new
research.

The so-called sunshine vitamin, which can be obtained from food or manufactured by
human skin exposed to the sun, plays a key role in boosting the immune system, researchers
believe.

In particular it triggers and arms the body's T cells, the cells in the body that seek
out and destroy any invading bacteria and viruses.

Scientists at the University of Copenhagen have discovered that Vitamin D is crucial to
activating our immune defences and that without sufficient intake of the vitamin, the
killer cells of the immune system  T cells  will not be able to react to and
fight off serious infections in the body.

For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses,
the cells must first be triggered into action and "transform" from
inactive and harmless immune cells into killer cells that are primed to seek out and
destroy all traces of invaders.

The researchers found that the T cells rely on vitamin D in order activate and they
would remain dormant, na´ve to the possibility of threat if vitamin D is
lacking in the blood.

Professor Carsten Geisler from the Department of International Health, Immunology and
Microbiology, said: "When a T cell is exposed to a foreign pathogen, it extends a
signalling device or antenna known as a vitamin D receptor, with which it
searches for vitamin D.

"This means that the T cell must have vitamin D or activation of the cell will
cease. If the T cells cannot find enough vitamin D in the blood, they wont even
begin to mobilise. 

The discovery, the scientists believe, provides much needed information about the
immune system and will help them regulate the immune response.

This is important not only in fighting disease but also in dealing with anti-immune
reactions of the body and the rejection of transplanted organs.

Active T cells multiply at an explosive rate and can create an inflammatory environment
with serious consequences for the body.

After organ transplants, T cells can attack the donor organ as a foreign
invader. In autoimmune diseases, like arthritis or Crohns Disease, T cells mistake
fragments of the bodys own cells for foreign invaders, leading to the body launching
an attack upon itself.

For the research team, identifying the role of vitamin D in the activation of T cells
has been a major breakthrough.

Scientists have known for a long time that vitamin D is important for calcium
absorption and the vitamin has also been implicated in diseases such as cancer and
multiple sclerosis, but what we didnt realise is how crucial vitamin D is for
actually activating the immune system  which we know now,  said the
researchers.

The findings, continues Professor Geisler, could help us to contain infectious
diseases and global epidemics.

They will be of particular use when developing new vaccines, which work precisely on
the basis of both training our immune systems to react and suppressing the bodys
natural defences in situations where this is important  as is the case with organ
transplants and autoimmune disease.

Most Vitamin D is produced as a natural by-product of the skins exposure to
sunlight. It can also be found in fish liver oil, eggs and fatty fish such as salmon,
herring and mackerel or taken as a dietary supplement.